Thermostat loses all settings (time, schedules) after a power cut.

Safety first: No hazardous work is required.

• Check for firmware updates: Use the Viessmann app to update the thermostat firmware to the latest version.
• Avoid rapid power cycling: Do not repeatedly switch power on and off; allow the device to shut down gracefully when possible.
• Reconfigure settings: After a power cut, re‑enter time and schedules and monitor whether they are retained on subsequent short outages.
• Replace thermostat: If settings are consistently lost, the internal memory or backup power is defective and the thermostat should be replaced.